Supporting bearing for linearly guided travelling units

ABSTRACT

A supporting bearing (17) for linearly guided travelling units, having a housing and having a roller (20) which contains a rolling-contact bearing (26) and is seated on an eccentric bolt (28) which is mounted rotatably in the housing and can be fixed by clamping bolts (27). The housing (18a, 18b) is composed of two housing halves (18a, 18b) which are preferably of the same construction. The axial position of the roller (20) is determined by inner wall regions (46) of the housing halves (18a, 18b), which are laid or pressed against the end sides of the inner raceway (27) of the roller (20) after radial adjustment of the roller (20), by clamping the housing halves (18a, 18b) together. This results in the axial position of the roller (20) being fixed directly by way of its inner raceway (27).

PRIOR ART

The invention takes as its departure point a supporting bearing forlinearly guided travelling units in accordance with the generic type ofthe main claim. In the case of supporting bearings of this generic type,which are used, in particular, in modular linear-guidance systems inindustrial manufacturing and themselves form a module for such a system,which can be designed individually, the axial play of the roller, aswell as the radial guidance play thereof, has to be eliminated beforestart-up of the travelling unit if the means for guiding the travellingunit are to be operated satisfactorily even after a relatively longoperating period. In the case of known supporting bearings of thegeneric type, the housing is configured rigidly in one part and isprovided, in order to receive the roller, with a cutout which is opentowards one housing side and of which the two side walls at right angleswith respect to the axis of the roller are spaced apart from one anotherby a non-changeable spacing which, due to the unavoidable manufacturingtolerances on the housing and the roller, usually results in axial playof the roller. In order to eliminate this, provision is made for a screwwhich is guided in the housing and butts, on a wedge surface, on theeccentric bolt and, by way of said surface, presses the eccentric boltaxially onto a fixed stop surface. In spite of the resulting fixing ofthe eccentric bolt, it is not ensured that the axial position of therollers also remains unchanged because the latter may possibly also bedisplaced on the eccentric bolt in the event of relatively high axialforces occurring.

ADVANTAGES OF THE INVENTION

The arrangement, according to the invention, having the characterizingfeatures of the main claim has the advantage that the axial position ofthe roller is fixed directly by way of its inner raceway and theeccentric bolt does not require an axial clamping surface. The twohousing halves may be of the same construction, as a result of which thenumber of items manufactured is increased and production is renderedless expensive. The two bearing pins on the eccentric bolt may have thesame diameter, with the result that, if appropriate, re-machining of thebearing bores in housing halves of the same construction is alsodispensed with.

The features cited in the subclaims constitute advantageous developmentsof the arrangement according to the main claim.

In the case of a preferred embodiment, the housing halves can be clampedtogether by the screws serving to fasten the supporting bearing on thebasic body of the travelling unit and are configured and/or dimensionedsuch that, at least on one housing half, the inner wall region locatedopposite the inner raceway of the roller is deformed inwards upontightening of the screws by the torque prescribed for the finalassembly. Consequently, the axial position of the roller isautomatically fixed, without additional measures and means, uponfastening the supporting bearing on the basic body of the travellingunit. Here, the arrangement may advantageously be such that deformationof the housing, eliminating the axial play, only takes place when thefastening screws of the supporting bearing are tightened to a greaterextent than is necessary for fixing the supporting bearing on the basicbody, during radial adjustment of the rollers and subsequently fixing ofthe eccentric bolt in the adjusted position. The radial adjustment ofthe roller takes place, in this case, in a pre-assembly operation, whilethe axial play is eliminated during the following final-assemblyoperation.

The features cited in claims 3, 4 and 5 give a configuration,appropriate for manufacturing, of a supporting-bearing housing composedof two halves of the same construction.

In the case of supporting bearings having at least one dirt scraperwhich serves at the same time for lubrication purposes, consists of feltand is mounted in a displaceable and spring-loaded manner in a guideshaft of the housing, it is proposed that the dirt scraper be providedwith border shoulders which, interacting with mating shoulders on thehousing, prevent undesired escape of the dirt scraper out of the guideshaft. This results in the fact that, during storage and/ortransportation of supporting bearings, specific measures against thedirt scraper falling out are dispensed with.

For a facilitated attachment of the supporting bearing on basic bodieswhich are provided with grooves for receiving fastening means, such ashammer nuts, the supporting-bearing housing is advantageously provided,on the assembly surface, with holes for plugging in guide elements whichserve for the initial adjustment of the supporting bearing on the basicbody and fit into the grooves.

DRAWING

An exemplary embodiment of the invention is explained in more detail inthe following description and represented in the drawing, in which:

FIG. 1 shows a side view of a linear guide with a travelling unitdesigned as a carriage,

FIG. 2 shows a supporting bearing of the travelling unit in thedirection of arrow A in FIG. 1,

FIG. 3 shows, on an enlarged scale, a section through the two looselyattached housing halves of the supporting bearing, along the lineIII--III in FIG. 2, and

FIGS. 4 to 6 show, likewise on an enlarged scale, sections through thepre-assembled, but not yet attached supporting bearing, along the linesIV--IV, V--V and VI--VI in FIG. 2.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The linear guide has a fixed guide rail 10 which is composed of anextruded profile 11 and of two steel running rails 12 which are fastenedon the extruded profile 11 in a suitable manner. The travelling unit,which is designated as a whole by the reference numeral 14 and isdesigned as a carriage, has, as basic body, a supporting plate 15 whichis formed by an extruded profile and is provided with longitudinallyrunning grooves 16 for receiving assembly elements for furthercomponents and component groups of the linear guide. Fastened on thatside of the supporting plate 15 which is directed towards the guide rail10 are four supporting bearings 17, of which, in the side view accordingto FIG. 1, in each case two lie congruently one behind the other. Thesupporting bearings 17 are designed as standardized modules of a modularconstruction system for linear guides which are suitable for attachmentonto different travelling-unit basic bodies which are adapted to therelevant application purpose.

Each supporting bearing 17 has a housing which is composed of twohousing halves 18a and 18b of the same construction and in which thereis rotatably mounted a roller 20 which butts against the guide rail 10.Each supporting bearing 18a is fastened on the supporting plate 15 bytwo screws 21 and two hammer nuts 22 which engage into a groove 16 inthe supporting plate 15 and also clamp the two housing halves 18a, 18btogether. For the facilitated pushing of the supporting bearing 17 ontothe supporting plate 15, and preliminary adjustment thereof, the housinghalf 18a is provided with two guide pins 23 which consist of an elasticmaterial, are plugged into blind bores 24 in the housing half 18a andfit into the introduction opening of the corresponding groove 16. Eachsupporting bearing 17 is further provided with two dirt scrapers 25which consist of felt and, in the manner described in more detailhereinbelow, are guided in the housing 18a, 18b and pressed against theguide rail 10 (the dirt scrapers 25 are not shown in FIG. 1).

Each roller 20 has a rolling-contact bearing 26, of which the innerraceway 27 is seated on an eccentric bolt 28 which is mounted rotatablyin corresponding bearing bores 29 in the two housing halves 18a, 18b. Byway of the eccentric bolt, the spacing of the roller 20 with respect tothe guide rail 10 can be adjusted, for which purpose the eccentric bolt28 is provided, on one end side, with attachment surfaces 30 for ascrewdriver. In order to fix the eccentric bolt 28 in the adjustedposition, use is made of a threaded stud 31 which engages into thethread of a hexagon nut 32, fixed without play in one housing half 18a,and presses radially against the eccentric bolt 28 in the region of thebearing bore 29. The operating-side end portion 33 of the threaded stud31 is located in an outwardly open cutout 34 of the housing half 18a,whereas the hexagon nut 32 is fitted in a pocket formed on the innerside of the housing half 18a.

The two housing halves 18a, 18b, which have the same construction andare attached in a mirror-inverted manner (FIG. 3), are designed suchthat they bear directly one upon the other only on their relativelynarrow side borders 36a, 36b. For this purpose, each housing half 18a,18b is provided, on one side border 36a, with two elevated bearingstrips 38, 39 which fit between shoulders 40, 41 and thus center thehousing halves 18a, 18b with respect to one another, said shouldersbeing formed on the other side border 36b on the transition to alower-lying wall portion 42. This results in a gap 43 being presentbetween the two housing halves 18a, 18b, said gap extending from oneside-border pair 36a, 36b to the other side-border pair 36b, 36a.

The bearing bores 29 for the eccentric bolt 28 are surrounded bycollar-like extensions 45 of the housing halves 18a, 18b, of which themutually facing stop surfaces 46, when the housing halves 18a, 18b arebearing one upon the other in a non-braced state, are spaced apart fromone another by a spacing L which corresponds at least to the length ofthe inner raceway of the roller 20 plus a small amount of play which isrequired for the adjustment of the radial position of the roller 20. Forthe accommodation and through-passage of the screws 21, the housinghalves 18a, 18b have stepped bores 47, 48 which are arranged between theside borders 36a, 36b and the center plane 49, of the housing 18a, 18b,which passes through the bearing bores 29.

The housing halves 18a, 18b are further provided with cutouts 50, 51which, located opposite one another in pairs, form in each case oneshaft for guiding a dirt scraper 25. Acting on each dirt scraper 25 is acompression spring 52 which is supported on the housing 18a, 18b via aball 53 and pushes the dirt scraper 25 outwards. Each dirt scraper 25has two border shoulders 54, 55 which, interacting with mating shoulders56, 57 on the housing 18a, 18b, delimit the displacement path towardsthe outside.

For the purposes of storage and delivery to the location of finalassembly, the individual parts of a supporting bearing 17 can be looselyheld together by the screws 21 and the hammer nuts 22 if these, as shownin FIG. 5, are screwed well enough onto the screws 21.

Upon assembly of the travelling unit 14 and play-free adaptation to theguide rail 10, the screws 21, after attachment of the supporting bearing17 onto the supporting plate 15, are first of all tightened only to theextent where the supporting bearings 17 are fixed in a captive manner,but there is no obstruction to radial adjustment of the rollers 20 dueto deformation of the housing half 18b which may, for example, alreadyhave occurred. After fixing of the eccentric bolt 28 by the threadedstud 31, the screws 21 are tightened by the full torque prescribed forfinal assembly, the housing half 18b, supported on the lateral bearingstrips 38, 39 being deformed inwards by all of its inner region untilits stop surface 46 comes to lie against the inner raceway 27 or pressesagainst the same with a predetermined force. The arrangement could alsobe such that the extension 45 bearing the stop surface 46 is therebydeformed to some extent.

We claim:
 1. Supporting bearing for linearly guided travelling units,having a housing which can be fastened on a basic body of the travellingunit by means of screws, and having at least one roller which contains arolling-contact bearing and of which the inner raceway is seated on aneccentric bolt which is mounted rotatably in the housing for radialadjustment of the roller and can be fixed in the adjusted position byclamping means, and further having means for eliminating the axial playand/or for fixing the axial position of the roller in the housing,characterized in that the housing of the supporting bearing (17) isdivided, transversely with respect to the axis of the roller (20), intotwo housing halves (18a, 18b) which are each provided with a bearingbore (29) for the eccentric bolts (28), and in that the axial positionof the roller (20) is fixed by inner wall regions (46) of the housinghalves (18a, 18b), which are laid or pressed against the end sides ofthe inner raceway (27) of the roller (20) after radial adjustment of theroller (20), by clamping the housing halves (18a, 18b) together. 2.Supporting bearing according to claim 1, characterized in that the twohousing halves (18a, 18b) are of the same construction.
 3. Supportingbearing according to claim 1 or 2, characterized in that the housinghalves (18a, 18b) can be clamped together by the fastening screws (21)serving to fasten the supporting bearing (17) on the basic body (15) ofthe travelling unit (14), and are configured and/or dimensioned suchthat, at least on one housing half (18a, 18b), the inner wall region(46) located opposite the inner raceway (24) of the roller (20) isdeformed inwards upon tightening of the screws (21) by the torqueprescribed for the final assembly.
 4. Supporting bearing according toclaim 3, characterized by the following features:a) the two housinghalves (18a, 18b) are configured such that they butt directly againstone another only on two opposite side borders (36a, 36b), b) thethrough-passage bores (47, 48) which are provided in the housing halves(18a, 18b) and are intended for the fastening screws (21) are arrangedbetween the bearing bores (29) and the abutting side borders (36a, 36b),c) formed on each housing half (18a, 18b) is a stop surface (46) whichsurrounds the inner opening of the bearing bore (29) and of which themutual axial spacing (L), when the housing halves (18a, 18b) are buttingagainst one another in a non-braced state, corresponds at least to thelength of the inner raceway (27) of the roller (20) plus an amount ofplay which permits rotation of the eccentric bolt (28).
 5. Supportingbearing according to claim 4, characterized in that the stop surfaces(46) which surround the inner openings of the bearing bores (29) areformed on collar-like extensions (45) of the housing halves (18a, 18b).6. Supporting bearing according to claim 1, characterized in that inorder to fix the eccentric bolt (28) in the adjusted position there isprovided a bracing screw (31), of which the operating-side end portion(33) is located in an outer cutout (34) of one housing half (18a) andwhich is rotatably mounted in a nut (32) which is retained in an innercutout of the housing half (18a) such that it is secured with respect torotation and axial displacement.
 7. Supporting bearing according toclaim 1, having at least one dirt scraper which consists of felt and ismounted in a displaceable and spring-loaded manner in a guide shaft ofthe housing, characterized in that the dirt scraper (25) is providedwith border shoulders (54, 55) which, interacting with mating shoulders(56, 57) on the housing (18a, 18b), prevent undesired escape of the dirtscraper (25) out of the guide shaft (50, 51).
 8. Supporting bearingaccording to claim 1, for fastening on a basic body which is formed byan extruded profile and is provided with longitudinal grooves forreceiving hammer nuts, characterized in that the housing (18a, 18b) ofthe supporting bearing (17) is provided, on the assembly surface, withholes (24) for plugging in guide elements (23) which serve to adjust thesupporting bearing (17) on the basic body (15) and fit into the grooves(16).